If red light is replaced by blue light in single slit diffraction then

The correct answer is Option (2) → diffraction bands become narrower

The position of diffraction minima (or dark fringes) is given by the condition -

$a\sin θ=nλ$

$∴λ↓∝θ↓$ [θ → Angle of Diffraction]

Hence, it results in smaller values of θ, so the fringe become close together.